The present invention relates to a thin-film magnetic head. More particularly, it relates to an induction type thin-film magnetic head having excellent reproducing and recording efficiencies and suited to high-density magnetic recording and reproduction. Specifically, it relates to a thin-film magnetic head effective for perpendicular magnetic recording.
The perpendicular magnetic recording method records a signal by magnetizing a face of a recording medium, such as magnetic tape and disk, in a vertical direction (thickness direction). It attains a high recording density unlike a conventional method which records a signal by magnetizing the recording medium substantially in a planar direction. As magnetic heads for the perpendicular magnetic recording, various types have hitherto been proposed. They include magnetic head structures for enhancing the recording density and for enhancing the vertical magnetic recording efficiency. However, these heads are generally low in the reproducing efficiency. Therefore, they have had the disadvantages (1) that a high output is difficult to be attained, (2) that in order to attain a high output, the number of turns of a coil needs to be increased, resulting in an increased inductance, and (3) that due to the increased inductance, the resonance frequency of the head lowers, the head being unusable especially in a high frequency region of above seveal MHz.
As an attempt to solve the disadvantages, it is considered to form a magnetic head for perpendicular recording by the use of the photolithographic technology as disclosed in Japanese Laid-open Patent Application No. 56-83826. It has been difficult, however, to realize a magnetic head which has a high recording density and a high reproducing efficiency, which is usable in a high frequency region and which has a satisfactory reliability for use over a long time.
The following references are cited to show the state of the art; (i) Japanese Laid-open Patent Application No. 52-55513, (ii) Japanese Laid-open Patent Application No. 56-83826.